Dengji Lou, Suping Lu, Zhen Chen, Yi Lin, Diqiu Yu, Xiaoyan Yang

BMC Plant Biol.; 2023 Jan 24;23(1):53. doi: 10.1186/s12870-023-04071-8.

Background: Many data suggest that the sucrose non-fermenting 1-related kinases 2 (SnRK2s) are very important to abiotic stress for plants. In rice, these kinases are known as osmotic stress/ABA-activated protein kinases (SAPKs). Osmotic stress/ABA-activated protein kinase 3 (OsSAPK3) is a member of SnRK2II in rice, but its function is still unclear.

Results: The expression of OsSAPK3 was up regulated by drought, NaCl, PEG and ABA. OsSAPK3 mutated seedings (sapk3-1 and sapk3-2) showed reduced hypersensitivity to exogenous ABA. In addition, under drought conditions, sapk3-1 and sapk3-2 showed more intolerance to drought, including decreased survival rate, increased water loss rate, increased stomatal conductance and significantly decreased expression levels of SLAC1 and SLAC7. Physiological and metabolic analyses showed that OsSAPK3 might play an important role in drought stress signaling pathway by affecting osmotic adjustment and osmolytes, ROS detoxification and expression of ABA dependent and independent dehydration-responsive genes. All gronomic traits analyses demonstrated that OsSAPK3 could improve rice yield by affecting the regulation of tiller numbers and grain size.

Conclusion: OsSAPK3 plays an important role in both ABA-dependent and ABA-independent drought stress responses. More interestingly, OsSAPK3 could improve rice yield by indirectly regulating tiller number and grain size. These findings provide new insight for the development of drought-resistant rice.

See https://pubmed.ncbi.nlm.nih.gov/36694135/

Fig. 3

OsSAPK3 mutated plants show decreased ABA sensitivity. A Sequence comparison of wild-type plants and two sapk3 mutant lines. B Protein structures of wild-type plants and two sapk3 mutant lines. C Transcript accumulation of OsSAPK3 in wild-type plants and two sapk3 mutant lines. D Phenotypes of wild-type plants and two sapk3 mutant lines before and after 100 μM ABA treatment for10 days. Scale bars = 2 cm. E Shoot and F Root length corresponding to D. Data represent means ± SD of three biological replicates (16 plants for each replicate). **P < 0.01 (Student’s t-test)